When double heterostructure light emitting devices are used as optical sources in optical communication systems, one of the problems involved is to accurately couple the light from the source into the optical communications fiber. The optical fiber core is generally constructed within specific design specifications for the purpose of mode selection and for reducing the dispersion time existing between the various modes. The diameter of the emitted light spot from the double heterostructure device is generally designed to provide the greatest quantity of light for the amount of electrical energy provided to the p-n junction of the device. One of the problems with existing optical communication systems is the difference in the geometry of the light spot generated by the double heterostructure device and the light carrying core of the optical communication fiber.
One method for compensating between the differential geometry of the optical fiber core and the dimensions of the light emitting spot of the double heterostructure device is to interpose a gradually tapering optical fiber wherein one end of the interposed fiber has a geometry comparable with that of the dimensions of the light emitting spot and the other end of the fiber is comparable with the core of the optical systems fiber.
The purpose of this invention is to provide an integrated optics device wherein the double heterostructure light emitter contains an integral waveguide and wherein the geometry of the light emitting spot and the exit angle of the light are determined by the properties of the waveguide. This now enables the light spot to be better matched to the light receiving core of the optical communication fiber. The integral waveguide can also be used to guide the emitted light around to modulators and switches (etc.) which can be integrated on a common substrate.